Reliability design of direct liquid cooled power semiconductor module for hybrid and electric vehicles

With the global interests and efforts in popularizing low carbon vehicles, automotive power module has been becoming one of the fastest growing sectors in power semiconductor industry. As working in a harsh environment, the performance and reliability requirements of automotive module are stringent than industrial products. In this work, an integrated direct liquid cooled power module with enhanced reliability for hybrid and electric vehicles (HEV/EV) is developed. The design and assembly of the module were optimized in terms of performance, weight, cost and reliability. The module is integrated Al direct liquid cooling structure, leading to about 40% reduction of weight and cost and almost 50% reduction of junction to heat sink thermal resistance. Therefore, the junction temperature stays below the upper limit at the worst operation case which enhances the thermal reliability and lifetime. By incorporating advanced die lead bonding, the parasitics can be reduced by 50%, which is beneficial to efficiency and reliability. Furthermore, the die and terminal attach technologies are investigated to improve reliability. The lifetime prediction under a typical driving cycle shows that the proposed module is capable of working in the whole vehicle service period.